As water fills up the underwater treadmill, Skinny lets out a string of meows in protest.

The tabby cat’s 15- to 20-minute walks on the treadmill might not be his favorite part of the day, but the morning workout has helped him lose about 15 pounds. That’s right — 15 pounds. A cat that once weighed 42 pounds and gained international fame has lost nearly a third of his girth.

His attending veterinarian and owner, Dr. Brittney Barton, hopes Skinny will continue to lose more weight, but she applauds his progress in the past year

“That’s an enormous amount of weight loss for a cat,” Barton said.

Last September, Skinny was found in the backyard of a Richardson residence. He was first taken to stay at the Richardson Animal Shelter.

Noura Jammal, resource coordinator at the shelter, said Skinny had such a hard time walking around that she is still unsure how he was able to get into the backyard in the first place.

Skinny’s size also made it difficult for veterinarians to determine gender. At first, he was thought to be a male. Then a female. And after another thorough examination, it was finally determined that Skinny was indeed a male cat.

The orange-and-white tabby attracted international fame as calls flooded into the shelter inquiring about adoption and news reports about the cat surfaced as far away as London.

“We had a lot of people donating money and time and wanting to see him, which was a good thing because it brought some positive attention to adoption and we had a lot of other animals that got adopted as well,” Jammal said.

After a brief stay at the shelter, Skinny moved to East Lake Pet Orphanage, where he could receive expert care for his large size. An average cat weighs 10-12 pounds, said Dennis Wooten, animal services manager at the Richardson Animal Shelter and assistant director of health for the city of Richardson.

Guinness Book of World Records does not list heaviest cats as a category, but Internet searches have revealed cats as heavy as nearly 47 pounds.

“Since he had such special needs, we just wanted to make sure that he was taken care of first and then get adopted out,” Jammal said.

Barton began her care of Skinny at East Lake. At that time, she said Skinny could only walk a range of five feet at a time.

“He couldn’t sustain his weight on his limbs,” she said.

To help Skinny shed pounds, Barton began reducing his calorie intake and explored options for physical activity. She also made efforts to make the cat feel comfortable in his new home giving him a TV and allowing occasional play time on cat-centered iPad apps.

Now, Skinny has a permanent home with the Barton family. He spends his weekdays at Barton’s newly opened HEAL Veterinary Hospital off Lemmon Avenue in Dallas, where he gets his daily exercise on the underwater treadmill.

Barton believes it’s the treadmill that has helped him begin losing weight again.

“I was stuck at about 30-31 pounds with him for longest time because you don’t want to starve it off of him because he still has vital nutrients and minerals that he needs to have every day to have a healthy body,” she said. “But to try and help wake up his metabolism a little bit we needed to help increase his muscle mass and increase exertion.”

Looking back to when she first met Skinny, Barton said the cat has made strides.

“As his weight loss has progressed and his personality has bloomed he’s moving better,” she said. “He can jump up on the couch, he can jump up on my bed, he can come out and seek out interaction much easier.”

She admits that Skinny has a bit of a food addiction. After Skinny ripped open bags of food at her clinic, Barton said she had to put up a safety gate, so he couldn’t get into the storage closet.

Skinny’s weight-loss journey is not over. For his next benchmark, Barton wants Skinny to weigh 22 pounds.

“I think just in general everybody just needs to keep cheering him on, feel free to come by and visit him and give him some love and affection and we are just going to keep pushing forward,” Barton said.